A new study has found that our shoulders hide the secret to human evolution. Researchers say that the last common ancestor that tied humans to chimpanzees may have had shoulders that resembled those of modern day African apes.
The research backs up the notion of humans gradually shifting away from tree habitats. It all started six (6) or seven (7) million years ago when human lineage started to diverge from chimpanzee lineage.
Now that filed experts are starting to learn more and more about the last common ancestor that tied humans to chimpanzees, they may soon be able to explain how the behavior and anatomy of both species evolved over the centuries. According to Nathan Young, evolutionary biologist from the University of California (San Francisco), the main thing that makes this difficult is that “fossils from that time are rare”.
Presently, scientists have two (2) different theories for what the last common ancestor that tied humans to chimpanzees may have looked like. One says that the animal looked very similar to modern day African apes (chimpanzees, gorillas). In fact, Young gave a statement to Live Science explaining that “A lot of people use chimpanzees as a model for the last common ancestor”.
But the second theory indicates that the similarities between the last common ancestor and modern day African apes may have evolved independently, and that the traits found in the last common ancestor may have been more primitive than those of modern day African apes.
One specific belief is that the last common ancestor may not have walked on the ground with its knuckles the way chimpanzees and gorillas do, but that it may have swung from branch to branch and hung from trees the way orangutans (Asian apes) do.
Young informed that humans beings are not the only species that has evolved and changed over the centuries. “Chimpanzees and gorillas have evolved and changed over time, too, so looking at their modern forms for insights into what the last common ancestor was like could be misleading in a lot of ways”.
Researchers give so much importance to the evolution of shoulders because they are tied to a lot of important changes in behavior in the evolution of the human lineage.
If field experts had a clear trajectory of shoulder evolution, they could see when exactly early humans started relying more on their tools, spending less time in trees, and learning how to throw weapons.
However, this trajectory has proven hard to reconstruct as human shoulders are unique in that they share traits with chimpanzee shoulders as well as orangutan shoulders.
In order to get a sense of what the last common ancestor’s shoulders may have looked like, Young and his colleagues generated several 3D models of shoulders from museum specimens that covered monkeys, gibbons, orangutans, gorillas, bonobos, chimpanzees and modern humans, and compared them to previously generated 3D models of ancient, extinct relatives of the modern human.
The research team concluded that human shoulders evolved gradually from an African apelike shape to their modern day shape
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